Formation tester sample chamber assembly



Dec. 8, 1953 e. H. RAMSEY 2,661,803

FORMATION TESTER SAMPLE CHAMBER ASSEMBLY Filed Sept. 25, 1952 3 Sheets-Sheet 1 George H.Qc1rn.se {50 2012 or atltloro e5 Dec. 8, 1953 G. H. RAMSEY FORMATION TESTER SAMPLE CHAMBER ASSEMBLY Filed Sept. 25, 1952 ill 3 Sheets-Sheet 2 Geor'3e -I-I. 12am$ bravehtor Dec. 8, 1953 e. H. RAMSEY v FORMATION TESTER SAMPLE CHAMBER ASSEMBLY Filed Sept. 25, 1952- 3 Sheets-Sheet 3 HIM w w n r 60 Q Patented Dec. 8, 1 953 FQBMATIDN TESTER SAMPLE CHAMBER, ASSEMBLY George H. Ramsey. Ardmore, Okla, assignor to Standard Oil Development Company, a corpm ration of Delaware m;121icatirmv September 25, 1952, Serial No. 311,467

This invention relates to animproved apparatus for the testing of; formations through which a hole is drilled" to determine possible oil-bearing strata. The invention is more particularly concerned with a sample chamber designedfor employment with suitable formation testers. The apparatus of the present invention comprises a balanced valve sample chamber designed for unsealing over a wide range of hydrostaticpressures. A particular feature of the present invention isa means for counterbal'ancing the downward force of the drilling mud, which would otherwise tend to prevent a sliding member of the valve from operating satisfactorily;

This application is a continuation-in-part ofapplication Serial; No. 123,027; filed October 22, 1949.

In conventional oil= well drilling operations, fluids lg-nown as drilling muds are employed toaid in carrying away cuttings and also to maintain a hydrostatic head in the well to prevent the uncontrolled escape of gases or liquids from various formations encountered during drilling. Gne disadvantage of drillingwith a drilling mud is that the sampling of'nat-ural fluids occourring in various formations is thereby rendered dinicult. 'Ifo overcome this disadvantage, various types of formation testers: have been devised which are provided? with, means for reducing the: hydrostatic pressure in the vicinity ofthe formation t; be tested, and for establishing communication between the formation and suitable conquits or; chambers for collecting thefluid samples with but little or no contamination by drilling.

mud: Eormation testing gives valuable information as to whether or not oil exists in the formation tested; Information can also, be obtained, relative to the possible productivity of; the well, the; pressure ofthe fluids in the rock formation, the; ratio of oil to gas, andthe occurrence of salt water.

Many of theseformation; testers are provided with, elastic sleevesor-packers for, sealing off the portion o f' -thewellinwhichit is desired. to reduce. thehydrostatic pressure. The use of'such elastic:

packers is particularly desirable since such a acker caa anded. o. iven tho ugnsear a'ndyetmay be readily removed from the well after being deflated. Furthermore it is possible to positionsuch an elastic packer at any desired point in the well with very little difiiculty. With.

formation testers of this type the use of a retrievable samplechamberis an lnvaluable; aid. Suclra sample chamber may be-run'in and out ofthe' bore hole rapidly and-"can give'positive iii-- 4% Claims. (Cl. 1669-1) formation as to the production of fluids from a given formation. If a pressure recorder is employed with the sample chamber a pressure record can be obtained, as an indication of conditions existing inthe formation. When using, a formation tester which may be relocated for any number of tests without withdrawing itfrom the hole, a retrievable sample chamber maybe used to determine theadvisability of conducting more extensive tests and many moresections of the well may be evaluated in a relatively short time. However, as the testing depth increases, the difficulty of removing a samplechamber from its seat in the formation testing tool increases. This is due to the hydrostatic head of the drilling mud, which tends to-keep the sample chamber in position-.-

It is an object of the present intention to:- pro vide a retrievable sample chamber for use: with: an oil well formation tester wherein the sample: chamber is adaptedto seat: on aconstriction. within the formation testeror within the drill; pipe associated with the-formation tester and: wherein the sample chamber may be readily: released from its sealed position when. it is desiredi to doso, regardless of the downward forcebeing; exerted" on the sample chamber by the drilling: mud. In accordance with this invention this. object is accomplished by providing within the: sample-chamber a sliding valve which is balancedz with regard to opposing-hydraulic forces, and by: providing means for equalizing pressures above and below the seating areaof the chamber when it is desired to free the sample chamber.

The nature and objects of; this invention. may. be more readilyunde-rstood' by'r'eference to: the: accompanying drawings in which:

Figure 1 is a perspective view, in quarter section, ofthe lower-portion of a sample chamber assembly inposition. within the top portion. of a drill stem" formation tester using an inflatable packer;

Figure 2 is anelevationalview in: section show.-

ing the sample chamb'erassenrbly just-above its.

the type disclosed in U. S. Patent 2,600,173 of Ben W. Sewell and George H. Ramsey, issued June 10, 1952, and is provided with production tubes 4 containing packing elements 5, an inflation channel 6 and a pressure equalizing channel 1. It is to be understood, of course, that the sample chamber assembly of this invention may also be used with other types of formation testers rather than the one illustrated.

The packer l is inflated by pumping drilling mud or other fluid down through the drill pipe into chamber 14 before the retrievable sample chamber has been lowered into place in the drill pipe. The inflation pressure for the inflatable packer may be controlled by any convenient means. For example, a special drill pipe section 3 may be provided with one or more orifices 13 so that fluid may be circulated down through the drill pipe and out through these orifices into the annulus between the drill pipe and the bore hole, thereby setting up a diiferential pressure between the mud inside the drill pipe and the mud surrounding the drill pipe in the vicinity of the packer. This differential pressure will be independent of the absolute or static pressure in the bore hole and will depend only on the size of the orifices and the mud circulation rate, so that a predetermined pressure is available for inflating the packer. This method of inflating a formation tester packer is described and claimed in co-pending application Ser. No. 202,172 of Ben W. Sewell, filed December 22, 1250.

Deflation of the packer prior to the completion of the test is prevented by a check valve iii backed by a spring H placed in the inflation channel 5.

When it is desired to deflate the packer, rod i2 may be depressed by a suitable tool lowered into the drill pipe so as to unseat valve iii. Such means are well known and need not be illustrated here. Escape of fluid from chamber it through conduit 8 and production tubes 4 during inflation of the packer is prevented by check valve [5.

After the packer has been inflated a sample chamber is run into the drill pipe on a wire line to collect a sample of the formation fluids through production tubes 4. A lower portion of such a sample chamber assembly is shown in Figure l, identified by numeral IT. The sample chamber assembly is provided with a sliding valve member having a tapered portion ie which is adapted to seat on a special shoulder [9 which defines the upper portion or a constricted section of the drill pipe. The sliding valve member is removably retained within the assembly by means of a removable split ring 41. A flexible sealing means comprising a flexible cup 20 is fastened to the bottom of the tapered member l8 by means of a ring 2| and a hex nut 22. This tapered flexible cup is adapted to fit compressibly within the constricted portion of the special drill pipe sec tion to ensure a tight fluid seal which will prevent passage of the drilling mud down into chamber I4 when the hydrostatic pressure is reduced in the latter chamber during the collection of the formation fluids. It is readily apparent that when it is desired to unseat the sample chamber assembly from its position against shoulder 19 and to release the packing cup 28 from the constricted section of the drill pipe the difierential pressure between the drilling mud above shoulder l9 and the fluid in chamber Hi will make such unseating diflicult. However, the valve arrangement about to be described overcomes this difficulty.

Referring now to Figures 2 and 3 itwill be seen 4 that the body of the sample chamber assembly comprises two sections, an upper section identifled by the numeral 16 within which the sample chamber 26 is positioned and a lower section I! which may be called the valve section. Within the valve section is a valve chamber 21 which slidably receives a valve element 28, which comprises an elongated piston, the lower portion of which extends below the body of the assembly and constitutes the tapered member l8 referred to in Figure 1.

An intermediate portion of valve element 28 is provided with cars 30 that fit slidably in slots 3| in valve section H. The slidable valve element is held in the position shown in Figure 2 by shear pins 32. The purpose of these shear pins is to prevent the accidental opening of the valve as the sample chamber assembly is lowered through the drill pipe. Valve element 28 is retained within valve chamber 21 by a split ring member 41 that is suitably fastened to the bottom of valve section ll as, for example, by recessed bolts. It will be seen that when member 41 is in place cars 30 will strike that member and prevent valve element 28 from sliding out of chamber 21'. Use of split rings of this nature, which are separable into two or more sections, is common practice when removal of an integral retaining ring from a cylindrical member is not possible because of interfering structure.

Valve element 28 is provided with a central conduit or channel 34 which terminates at its lower end in an ex erior port 35 below the packing cup 29 and which terminates at its upper end in a side port 33. Valve chamber 21 is provided at its upper end with a pressure equalizing port 40 which terminates exterior of the valve chamher body. The valve chamber 21 has a central portion 3? of larger bore than the diameter of the valve element 28 and channel 39 is provided to establish fluid communication between the enlarged central portion 37 and the sample chamber 28. Ring seals 42, t3, and 44, mounted in grooves on valve element 23 prevent fluid leakage past this element where it fits slidably within the valve chamber.

It will be noted that with valve element 28 in the position shown in Figure 2, i. e. in the position it assumes as the sample chamber assembly is lowered through the drill pipe, channel 34 provides a path for the flow of drilling mud or other fluid from the region exterior of the assembly below the sealing cup 20 to a region exterior of the assembly above the sealing cup, since port 36 in this position of the valve element registers with one of the slots 3|, this slot serving as a side port for the valve chamber. Thus as the tapered member !8 comes to seat on shoulder l9 and flexible cup 22 enters the constricted portion of the drill pipe, fluid thereby displaced from the constricted area is free to flow up through channel 34 and out through the slot 3!. This ensures that the assembly will seat properly on the shoulder provided. The sample chamber assembly is lowered with suficient momentum so that on the impact of seating member IS on shoulder IS the pins will be caused to shear. Thus member ll will continue to travel downward, sliding on element 28 until the bottom end of member ll comes to rest on shoulder 29 at the top of tapered member Ill. The valve will then be in the position shown in Figure 3.

With the sample chamber assembly seated in position and with valve member 28 in the position shown in Figure 3,1iuid communication is established between chamber l4 and sample chamber 2'6, the fluid path being provided by channel 34, the enlarged bore 31 and channel 39. As the pressure within chamber 26 is originally at atmospheric pressure or lower whereas the formation pressure is substantially above such pressure, formation fluid will flow into the sample chamber from the production tubes 4 and chamber [4 through the fluid path just described.

After the fluid sample has been secured, the sample chamber is pulled upward by the wire line on which it was lowered into the drill pipe. The arrangement for raising and lowering the sample chamber on the wire line is conventional and hence is not shown in the drawing. As the assembly begins to move upward in the drill pipe, the hydrostatic head of the drilling mud exerted on the sliding valve element 28 above the sealing cup 20 will hold member l8 in position on shoulders I9 until the valve chamber body I! has slid upwardly with respect to element 28 to the position shown in Figure 2. It will be seen that at this time the enlarged bore 31 will be closed off by element 28 so that fluids within chamber 26 cannot escape and at the same time fluid communication is again established between fluid in the drill pipe above the sealing cup 20 and fluid in chamber I4. Thus fluid pressures above and below the sealing cup 20 and above and below the 'member l8 become equalized and the seal established by member 3 and cup 20 is readily released.

It will be noted further that any tendency for fluid forces within the drill pipe to move valve element 28 upwardly and thus release fluids from chamber 26 through channel 34 is overcome by the provision of pressure equalizing port 40 positioned above the top of element 28. The top portion of element 28 is of the same diameter as the body of the element so that the top of the element acts as an equalizing piston. Thus any fluid force tending to move element 28 upwardly is overcome by an equal fluid force bearing down on the area 38.

A noteworthy feature of the sample chamber assembly of this invention is that valve element 28 is the only moving part and that all of the pressure seals associated with the valve may be inspected by merely removing this one moving part. For this purpose it is merely necessary to remove the split ring 41 from the lower end of member I1, whereupon valve element 28 will be free to slide out of valve chamber 21.

It is not intended that this invention be limited to the specific embodiments herein described as many modifications thereof are possible without departing from the scope of the invention.

What is claimed is:

1. Improved apparatus for collecting a sample of fluid from the lower end of a drill pipe comprising, in combination, a body adapted to be lowered into said drill pipe, a fluid retaining chamber in said body, a valve chamber in said body, a valve element slidably arranged in said valve chamber, said valve element comprising an elongated piston extending below said body and having a portion adapted for seating on a constriction in said drill pipe, said valve chamber having a first port at its upper end above said valve element and a second port intermediate its ends, both of said ports terminating exterior of said body, a first conduit in said body connected to said fluid retaining chamber and terminating within said valve chamber, a central conduit within said valve element terminating at one end below said seating portion and at the other end exterior of said valve element at a point intermediate its ends, said valve element assuming within said valve chamber a first position wherein said central conduit is placed in fluid communication with said second port of said valve chamber, and movable to a second position wherein said central conduit is placed in communication with said first conduit, said first port in said valve chamber serving to transmit fluid pressure in said drill pipe to the top of said piston, whereby fluid pressure tending to force said piston upward is counterbalanced.

2. Improved apparatus according to claim 1 including packing means supported on said valve element adjacent said seating portion and adapted for fluid sealing engagement with said drill pipe constriction.

3. Improved apparatus according to claim 1 including shear pins releasably holding said valve element in said first position.

4. Improved apparatus for collecting a sample of fluid from the lower end of a drill pipe comprising, in combination, a body adapted to be lowered into said drill pipe, a fluid retaining chamber in said body, a valve chamber in said body, a valve element slidably arranged in said valve chamber, said valve element comprising an elongated piston extending below said body and having a portion adapted for seating on a constriction in said drill pipe, said valve chamber having a central portion of larger bore than said valve element and having a first port at its upper end above said valve element and a second port intermediate its ends, both of said ports terminating exterior of said body, a conduit in said body connecting. said enlarged bore of said valve chamber with said fluid retaining chamber and a central conduit within said valve element terminating at one end in a side port exterior of said valve element at a point intermediate the ends of said valve element, and terminating at the other end in a bottom port exterior of said valve element below said seating portion, said valve element assuming within said valve chamber a first position wherein said side port communicates with said second port of said valve chamber and movable to a second position wherein said side port communicates with said enlarged bore of said valve chamber, said first port in said valve chamber serving to transmit fluid pressure in said drill pipe to the top of said piston, whereby fluid pressure tending to force said piston upward is counterbalanced.

GEORGE H. RAMSEY.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date y 2,308,387 Potts Jan. 12, 1943 2,613,747 West Oct. 14, 1952 

